fix: apply message serialization fix everywhere

Moving this to a serializer function like done with a couple other models guarantees getting messages with pending acks won't fail elsewhere. It also sets it up so the we can add/remove properties on the Message model as needed in the future.

related: 51a1028588

src/structures/Chat.js

@@ -162,7 +162,7 @@ class Chat extends Base {
             }
 
             msgs.sort((a, b) => (a.t > b.t) ? 1 : -1);
-            return msgs.splice(msgs.length - limit).map(m => m.serialize());
+            return msgs.splice(msgs.length - limit).map(m => window.WWebJS.getMessageModel(m));
 
         }, this.id._serialized, searchOptions.limit);